| static const char *hb_gpu_vertex_msl = |
| "/*\n" |
| " * Copyright (C) 2026 Behdad Esfahbod\n" |
| " * Copyright (C) 2017 Eric Lengyel\n" |
| " *\n" |
| " * Based on the Slug algorithm by Eric Lengyel:\n" |
| " * https://github.com/EricLengyel/Slug\n" |
| " *\n" |
| " * This is part of HarfBuzz, a text shaping library.\n" |
| " *\n" |
| " * Permission is hereby granted, without written agreement and without\n" |
| " * license or royalty fees, to use, copy, modify, and distribute this\n" |
| " * software and its documentation for any purpose, provided that the\n" |
| " * above copyright notice and the following two paragraphs appear in\n" |
| " * all copies of this software.\n" |
| " *\n" |
| " * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR\n" |
| " * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES\n" |
| " * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN\n" |
| " * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH\n" |
| " * DAMAGE.\n" |
| " *\n" |
| " * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,\n" |
| " * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND\n" |
| " * FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS\n" |
| " * ON AN \"AS IS\" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO\n" |
| " * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.\n" |
| " */\n" |
| "\n" |
| "\n" |
| "/* Requires Metal Shading Language 2.0. */\n" |
| "\n" |
| "\n" |
| "/* Dilate a glyph vertex by half a pixel on screen.\n" |
| " *\n" |
| " * position: object-space vertex position (modified in place)\n" |
| " * texcoord: em-space sample coordinates (modified in place)\n" |
| " * normal: object-space outward normal at this vertex\n" |
| " * jac: inverse of the 2x2 linear part of the em-to-object transform,\n" |
| " * stored row-major as (j00, j01, j10, j11). Maps object-space\n" |
| " * displacements back to em-space for texcoord adjustment.\n" |
| " * For simple scaling with y-flip (the common case):\n" |
| " * em-to-object = [[s, 0], [0, -s]]\n" |
| " * jac = (1/s, 0, 0, -1/s)\n" |
| " * m: model-view-projection matrix\n" |
| " * viewport: viewport size in pixels\n" |
| " */\n" |
| "void hb_gpu_dilate (thread float2& position, thread float2& texcoord,\n" |
| " float2 normal, float4 jac,\n" |
| " float4x4 m, float2 viewport)\n" |
| "{\n" |
| " float2 n = normalize (normal);\n" |
| "\n" |
| " float4 clipPos = m * float4 (position, 0.0, 1.0);\n" |
| " float4 clipN = m * float4 (n, 0.0, 0.0);\n" |
| "\n" |
| " float s = clipPos.w;\n" |
| " float t = clipN.w;\n" |
| "\n" |
| " float u = (s * clipN.x - t * clipPos.x) * viewport.x;\n" |
| " float v = (s * clipN.y - t * clipPos.y) * viewport.y;\n" |
| "\n" |
| " float s2 = s * s;\n" |
| " float st = s * t;\n" |
| " float uv = u * u + v * v;\n" |
| "\n" |
| " float denom = uv - st * st;\n" |
| " float d = abs (denom) > 1.0 / 16777216.0\n" |
| " ? s2 * (st + sqrt (uv)) / denom\n" |
| " : 0.0;\n" |
| "\n" |
| " float2 dPos = d * normal;\n" |
| " position += dPos;\n" |
| " texcoord += float2 (dot (dPos, jac.xy), dot (dPos, jac.zw));\n" |
| "}\n" |
| ; |
